A printer which prints information such as a desired character or image on a sheet-like printing medium such as a paper sheet or film is widely used as an information output apparatus in a wordprocessor, personal computer, facsimile apparatus, and the like.
Various methods are known as printing methods for the printer. Especially an inkjet method has recently received a great deal of attention because this method can realize noncontact printing on a printing medium such as a paper sheet, easily prints in color, and is quiet. Because of low cost and easy downsizing, a popular inkjet arrangement is a serial printing system in which a printhead for discharging ink in accordance with desired printing information prints while reciprocally scanning in a direction crossing to the convey direction of a printing medium such as a paper sheet.
There has conventionally been known a printing apparatus which divides the printing region of a printhead in the scanning direction into a plurality of regions and has a buffer for storing printing data of each divided region, in order to print by scanning a carriage mounting the printhead on a printing medium.
The printing apparatus comprises a write controller which controls, for each color, write address information of printing data of each region on the basis of information for switching the data storage area for each color and the result of a comparison between the remaining storable buffer space and the write address update amount when printing data of each divided region is to be stored in the buffer (Japanese Patent Laid-Open No. 2003-305896).
The printing apparatus further comprises a read controller which controls, for each color, read address information for reading out printing data stored in the buffer, and a printing data generation means for generating printing data of each divided region in accordance with printing data read out on the basis of the read address information.
Printing data transferred from a host computer to the conventional printing apparatus having this arrangement undergoes positional adjustment (registration adjustment) in the scanning direction (raster direction) by the host computer (printer driver) (Japanese Patent Laid-Open No. 2003-305895).
Printing data transferred to a printing apparatus is generally expressed by 1 bit (binary) representing printing/non-printing. However, the data processing unit of a host computer is generally set to 16 or 32 bits.
It is, therefore, not efficient to process 1-bit data such as printing data by the host computer, and the process takes a long time.
The resolution of printing apparatuses has recently increased, and the printing data amount transferred from the host computer to the printing apparatus has also increased. As the printing data amount increases, generation of printing data by the host computer takes a longer time. An effective speed until the printing apparatus executes printing upon designation of printing decreases.
For this reason, it is indispensable to shorten a time taken to generate printing data to be transferred from the host computer (printer driver) to the printing apparatus and a time until printing is executed upon designation of printing.